#include <stdio.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <pthread.h>


void perr_exit (const char *s){
	perror(s);
	exit(-1);
}

void sys_err(const char *s){
	perror(s);
	exit(-1);
}


int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr)
{
	int n;

again:
	if((n = accept(fd, sa, salenptr)) < 0){
		if ((errno == ECONNABORTED) || (errno == EINTR))
			goto again;
		else
			perr_exit("accept error");
	
	}
	return n;
}

int Bind(int fd, const struct sockaddr *sa, socklen_t salen)
{
	int n;

	if ((n = bind(fd, sa, salen)) < 0)
		perr_exit("bind error");

	return n;

}

int Connect(int fd, const struct sockaddr *sa, socklen_t salen)
{
	int n;

	n = connect(fd, sa, salen);
	if (n < 0){
		perr_exit("connect error");
	}

	// if ((n = connect(fd, sa, salen)) < 0)
	// 	perr_exit("connect error");

	return n;

}

int Listen(int fd, int backlog){
	int n;
	if ((n = listen(fd, backlog)) < 0)
		perr_exit("listen error");

	return n;
}

int Socket(int family, int type, int protocol){
	int n;
	if ((n = socket(family,type,protocol)) < 0)
		perr_exit("socket error");

	return n;
}

ssize_t Read(int fd, void *ptr, size_t nbytes)
{
	ssize_t n;

again:
	if ((n = read(fd, ptr, nbytes)) == -1){
		if (errno == EINTR)
			goto again;
		else
			return -1;
	}
	
	return n;
}

ssize_t Write(int fd,const void *ptr, size_t nbytes)
{
	ssize_t n;

again:
	if ((n = write(fd, ptr, nbytes)) == -1){
		if (errno == EINTR)
			goto again;
		else
			return -1;
	}
	
	return n;
}

int Close(int fd)
{
	int n;
	if ((n = close(fd)) == -1)
		perr_exit("close error");

	return n;
}

/* args three: should read bytes */
ssize_t Readn(int fd, void *vptr, size_t n)
{
	size_t nleft;   //unsigned int: Number of remaining unread bytes
	ssize_t nread;  //int :Number of actual bytes read
	char *ptr;

	ptr = vptr;
	nleft = n;

	while (nleft > 0){
		if ((nread = read(fd, ptr, nleft)) < 0){
			if (errno == EINTR)
				nread = 0;
			else
				return -1;
		}else if (nread == 0)
			break;

		nleft -= nread;  // nleft = nleft - nread
		ptr += nread;
	}
	return n - nleft;

}

ssize_t Writen(int fd, const void *vptr, size_t n)
{
	size_t nleft;
	ssize_t nwritten;
	const char *ptr;

	ptr = vptr;
	nleft = n;
	while (nleft > 0){
		if ((nwritten = write(fd, ptr, nleft)) <= 0){
			if (nwritten < 0 && errno == EINTR)
				nwritten = 0;
			else
				return -1;
		}

		nleft -= nwritten;
		ptr += nwritten;
	}
	return n;
}

static ssize_t my_read(int fd, char *ptr)
{
	static int read_cnt;
	static char *read_ptr;
	static char read_buf[100];

	if (read_cnt <= 0){
again:
		if ((read_cnt = read(fd, read_buf, sizeof(read_buf))) < 0){
			if (errno == EINTR)
				goto again;
			return -1;
		}else if (read_cnt == 0)
			return 0;

		read_ptr = read_buf;
	
	}
	read_cnt--;
	*ptr = *read_ptr++;

	return 1;

}

ssize_t Readline(int fd, void *vptr, size_t maxlen)
{
	ssize_t n, rc;
	char c, *ptr;
	ptr = vptr;

	for (n = 1; n < maxlen; n++){
		if ((rc = my_read(fd, &c)) == 1){ // ptr[] = hello\n
			*ptr++ = c;
			if (c == '\n')
				break;
		}else if (rc == 0){
			*ptr = 0;
			return n-1;
		}else
			return -1;
	}
	*ptr = 0;

	return n;
}




